**Student1:** |
**so if you increase one you have to
decrease the other to make it multiply to 250.** |

**Teacher :** |
**What did you do to the radius to get
the base area?** |

**Student:** |
**Pi-r-squared... ?** |

**Teacher :** |
**What did you do to the radius to get
the base area?** |

**Student1:** |
**It's, ah, pi-r-squared, so you...** |

**Teacher :** |
**Pi-r-squared. I want you to think
about the x-axis. As the radius goes up by one,** |

**Teacher :** |
**think about radius squared. The radius
is one, what's r-squared?** |

**Student:** |
**One ** |

**Teacher :** |
**One. If the radius is 2, what's r-squared?** |

**Student:** |
**4** |

**Teacher :** |
**4. So it jumped by...** |

**Student:** |
**3.** |

**Teacher :** |
**If the radius goes up to 3, what's
r-squared?** |

**Student:** |
**9.** |

**Teacher:** |
**9. So it jumped by...** |

**Student:** |
**6. ** |

**Teacher :** |
**5. So as your radius goes up by 1,
your height is changing ** |

**Teacher :** |
**because you're squaring the radius.
We haven't really had a problem like that before.** |

**Teacher :** |
**But your radius is getting squared,
isn't it? ** |

**Teacher :** |
**And so it isn't changing by a constant
amount, it's squared.** |

**Teacher :** |
**But just to correct you, on the x-axis,
is the radius going up by a constant amount?** |

**Student:** |
**Yes.** |

**Teacher :** |
**Yes. The radius goes up by a constant
amount...** |

**Teacher :** |
**Yes. The radius goes up by a constant
amount...** |

**Teacher :** |
**Yes. The radius goes up by a constant
amount...** |

**Student1:** |
**But the base area isn't. ** |

**Teacher :** |
**Right. Because of the squaring...
Okay, good. Okay, number three,** |

**Teacher :** |
**Right. Because of the squaring...
Okay, good.** |